1. Field of the Invention
The present invention relates to a method of manufacturing a flat panel display of a type having a pattern of constituent elements arranged in correspondence with an arrangement of cells in a display region.
2. Description of the Prior Art
In the course of mass production of flat panel displays (FPDs) such as, for example, plasma display panels, liquid crystal display panels and organic electroluminescence display panels, attempts have hitherto been made to minimize indirect materials of a kind utilized solely for the convenience of manufacture thereof. The indirect materials are, when intended products are completed, in most cases disposed of as wastes and, therefore, the need has been well recognized to minimize the indirect materials not only to avoid concomitant increase of the manufacturing cost, but also to avoid environmental contamination.
In general, photolithography has hitherto been used to form electrodes employed in the flat panel displays. Specifically, in the manufacture of the conventional flat panel displays, using thin-film technology such as, for example, a vacuum deposition technique or a chemical vapor deposition (CVD) technique is used to form an electroconductive film on a substrate so as to cover the entire surface area of the substrate, followed by the pattern exposure subjected to a photoresist to form an etching mask. Thereafter, unnecessary portions of the electroconductive film on the substrate are chemically or physically etched off to thereby complete formation of the electrodes. The practice of such a photolithography requires a substantial amount of indirect materials such as, for example, photoresist and developing material and renders it difficult to secure the pattern accuracy as the screen size of the flat panel display increases.
The Japanese Laid-open Patent Publication No. 2000-292489, published in 2000, discloses a method of making electrodes used in a plasma display panel (PDP), in which the electroconductive film is patterned by the use of a laser beam machining. In the practice of such laser beam machining, a light shielding mask of a size sufficiently smaller than the screen size is used so that portions of the electroconductive film can be irradiated in a pattern with a laser beam to remove those unnecessary portions of the electroconductive film. The electroconductive film in its entirety is then patterned while the substrate bearing the electroconductive film is moved relative to a laser irradiating system including the light shielding mask. As is well known to those skilled n the art, the patterning performed by the use of the laser irradiation along with the use of the light shielding mask is considered having a higher workability than that achieved by the patterning based on the delineating scheme utilizing a spot irradiation. Also, since the light shielding mask used in such laser patterning is small, a desired pattern accuracy can be secured regardless of the screen size.
In the manufacture of the conventional FPDs, however, although the use of the laser beam machining to form the electrodes is effective to reduce the amount of the indirect materials used as compared with that in the practice of the photolithography, a problem has hitherto been recognized in which residual dross responsible for surface defects tends to accumulate considerably. Also, another problem is also recognized in which defects in patterning such as edge swelling of the patterned electrodes resulting from influence brought about by heat evolved during the laser beam irradiation tend to be formed easily.